MIC6315-44DUY - Micrel, Inc.

February 2005 1 M9999-031104

MIC6315 Micrel, Inc.

MIC6315

Open-Drain µP Reset Circuit

General Description

The MIC6315 is an inexpensive reset generator circuit that

monitors power supplies in microprocessor based systems.

The function of this device is to assert a reset if either the

power supply drops below a designated reset threshold level

or /MR is forced low. Several different reset threshold levels

are available to accommodate 3V, 3.3V or 5V powered

systems.

The MIC6315 has an active low, open-drain /RESET output.

The reset output is guaranteed to remain asserted for a

minimum of either 20ms, 140ms, or 1100ms after VCC has

risen above the designed reset threshold level. The MIC6315

comes in a 4-pin SOT-143 package.

Typical Application

VCC

RESET

µP

RESET

VCC

MIC6315

VCC

10k

Features

•Precision voltage monitor for 3V, 3.3V or 5V power

supplies

•/RESET remains valid with VCC as low as 1.4V

•<15µA supply current

•20ms, 40ms, or 1100ms minimum reset pulse widths

available

•Manual reset input

•4-pin SOT-143 package

Applications

•Portable equipment

•Intelligent instruments

•Critical microprocessor power monitoring

• Printers/computers

•Embedded controllers

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

MIC6315 Micrel, Inc.

M9999-031104 2February 2005

Pin Description

Pin Number Pin Name Pin Function

1GND IC Ground Pin.

2/RESET /RESET goes low if VCC falls below the reset threshold and remains asserted

for one reset timeout period after VCC exceeds the reset threshold.

3/MR Manual Reset Input. A logic low on /MR forces a reset. The reset will remain

asserted as long as /MR is held low and for one reset timeout period after /MR goes

high. This input can be shorted to ground via a switch or be driven by TTL or CMOS

logic. Float if unused.

4VCC Power Supply Input.

Pin Configuration

4VCC

GND

MIC6315

RESET 3

MIC6315-xxDyU 4-Lead SOT-143

Ordering Information(1, 2)

Standard Pb-Free Min. tRST Operating

Part Number Marking Part Number Marking* VTH (V) (ms) Temp Range Package

MIC6315-26D2U NY MIC6315-26D2UY NY 2.63 20 –40°C to +85°C4-lead SOT-143

MIC6315-29D2U NM MIC6315-29D2UY NM 2.93 20 –40°C to +85°C4-lead SOT-143

MIC6315-30D2U N2 MIC6315-30D2UY N2 3.00 20 –40°C to +85°C4-lead SOT-143

MIC6315-31D2U zz MIC6315-31D2UY zz 3.08 20 –40°C to +85°C4-lead SOT-143

MIC6315-40D2U NW MIC6315-40D2UY NW 4.00 20 –40°C to +85°C4-lead SOT-143

MIC6315-41D2U N6 MIC6315-41D2UY N6 4.10 20 –40°C to +85°C4-lead SOT-143

MIC6315-44D2U zz MIC6315-44D2UY zz 4.38 20 –40°C to +85°C4-lead SOT-143

MIC6315-46D2U zz MIC6315-46D2UY zz 4.63 20 –40°C to +85°C4-lead SOT-143

MIC6315-26D3U NR MIC6315-26D3UY NR 2.63 140 –40°C to +85°C4-lead SOT-143

MIC6315-29D3U NP MIC6315-29D3UY NP 2.93 140 –40°C to +85°C4-lead SOT-143

MIC6315-30D3U N3 MIC6315-30D3UY N3 3.00 140 –40°C to +85°C4-lead SOT-143

MIC6315-31D3U NU MIC6315-31D3UY NU 3.08 140 –40°C to +85°C4-lead SOT-143

MIC6315-40D3U N8 MIC6315-40D3UY N8 4.00 140 –40°C to +85°C4-lead SOT-143

MIC6315-41D3U N5 MIC6315-41D3UY N5 4.10 140 –40°C to +85°C4-lead SOT-143

MIC6315-44D3U zz MIC6315-44D3UY zz 4.38 140 –40°C to +85°C4-lead SOT-143

MIC6315-46D3U NX MIC6315-46D3UY NX 4.63 140 –40°C to +85°C4-lead SOT-143

MIC6315-26D4U NS MIC6315-26D4UY NS 2.63 1100 –40°C to +85°C4-lead SOT-143

MIC6315-29D4U NN MIC6315-29D4UY NN 2.93 1100 –40°C to +85°C4-lead SOT-143

MIC6315-30D4U N4 MIC6315-30D4UY N4 3.00 1100 –40°C to +85°C4-lead SOT-143

MIC6315-31D4U zz MIC6315-31D4UY zz 3.08 1100 –40°C to +85°C4-lead SOT-143

MIC6315-44D4U N9 MIC6315-44DUY N9 4.00 1100 –40°C to +85°C4-lead SOT-143

MIC6315-44D4U N7 MIC6315-44DUY NY 4.10 1100 –40°C to +85°C4-lead SOT-143

MIC6315-44D4U zz MIC6315-44D4UY zz 4.38 1100 –40°C to +85°C4-lead SOT-143

MIC6315-46D4U NZ MIC6315-46D4UY NZ 4.63 1100 –40°C to +85°C4-lead SOT-143

1All devices available in tape and reel only.

2Parts not yet assigned an identification code are shown as “zz”. Contact Micrel for details. Minimum order may apply.

*Under bar symbol (_) may not be to scale.

February 2005 3 M9999-031104

MIC6315 Micrel, Inc.

Electrical Characteristics

For typical values, VCC = 2.5V to 5.5V, TA = 25°C; bold values indicate –40°C ≤ TA ≤ +85°C; unless noted

Symbol Parameter Condition Min Typ Max Units

Operating Voltage Range 1.4 5.5 V

ICC Supply Current VCC = 5.5V, no load 9 15 µA

VCC = 3.6V, no load 6 10 µA

VTH Reset Voltage Threshold Note 4 VTH–2.5% VTH VTH+2.5% V

tRST Reset Timeout Period 20 28 44 ms

140 200 320 ms

1100 1500 2500 ms

VOL /RESET Output Voltage VCC > 4.25V, ISINK = 3.2mA 0.4 V

VCC > 2.5V, ISINK = 1.2mA 0.3 V

VCC > 1.4V, ISINK = 50µA0.3 V

/RESET Output Leakage /RESET deasserted 1µA

/MR Minimum Pulse Width 10 µs

/MR to Reset Delay 0.5 µs

VIH /MR Input Threshold VTH > 4.0V 2.3 V

VTH > 4.0V 0.7××

××

×VCC V

VIL /MR Input Threshold VTH > 4.0V 0.8 V

VTH > 4.0V 0.25××

××

×VCC V

/MR Pull-Up Resistance 10 20 30 kΩ

/MR Glitch Immunity 100 ns

Notes:

1. Exceeding the absolute maximum rating may damage the device.

2. The device is not guaranteed to function outside its operating rating.

3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

4. Various reset thresholds available. See ordering information or contact factory.

Absolute Maximum Ratings(1)

Terminal Voltage

(VCC, /RESET) ...................................... –0.3V to 6.0V

(/MR) ........................................ –0.3V to (VCC + 0.3V)

Rate of Rise (VCC) ................................................. 100V/µs

Input Current (VCC, /MR) ............................................ 20mA

Output Current (/RESET) ........................................... 20mA

Lead Temperature (soldering, 10 sec.) ..................... 300°C

Storage Temperature (TS)........................ –65°C to 150°C

ESD Rating(3)

Operating Ratings(2)

Operating Temperature Range .................. –40°C to +85°C

Input Voltage (/RESET).................................... GND – 5.5V

Power Dissipation (TA = +70°C) .............................. 320mW

MIC6315 Micrel, Inc.

M9999-031104 4February 2005

Functional Diagram

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 

   

 





 

Timing Diagram

/MR

/RESET

RST

Reset Timing Diagram

February 2005 5 M9999-031104

MIC6315 Micrel, Inc.

Applications Information

Microprocessor Reset

The /RESET pin is asserted whenever VCC falls below the

reset threshold voltage or if /MR (manual reset) is forced low.

The /RESET pin remains asserted for the duration of the reset

timeout period after VCC has risen above the reset threshold

or /MR has returned high. The reset function ensures the

microprocessor is properly reset and powers up in a known

condition after a power failure. /RESET will remain valid with

VCC as low as 1.4V.

The /RESET output is a simple open-drain N-channel MOS-

FET structure. A pull-up resistor must be used to pull this

output up to some voltage. For most applications, this voltage

will be the same power supply that supplies VCC to the

MIC6315. It is possible however to tie this resistor to some

other voltage. This will allow the MIC6315 to monitor one

voltage while level-shifting the /RESET output to some other

voltage. The pull-up voltage must be limited to 6.0V or less

(absolute maximum) to avoid damage to the MIC6315. The

resistor must be small enough to supply current to the inputs

and leakage paths that are driven by the /RESET output.

/RESET Valid at Low Voltage

As VCC drops to 0V, the MIC6315 will no longer be able to pull

the /RESET output low. At this point, the pull-up resistor will

pull the output high. The value of the pull-up resistor and the

voltage it is connected to will affect the point at which this

happens.

Wire OR'ing The /RESET Output

Because the RESET output is open-drain, several reset

sources can be wire-ORed in parallel to allow resets from

multiple sources.

VCC Transients

The MIC6315 is relatively immune to negative-going VCC

glitches below the reset threshold. Typically, a negative-

going transient 125mV below the reset threshold with a

duration of 25µs or less will not cause an unwanted reset. If

additional transient immunity is needed, a bypass capacitor

can be placed a close as possible to the MIC6315.

VCC

RESET

5V SYSTEM

RESET

VCC

MIC6315

+5.0V

10k

+3.3V

MIC6315 Used in a Multiple Supply System

MIC6315 Micrel, Inc.

M9999-031104 6February 2005

Package Information

0.150 (0.0059)

0.089 (0.0035)

8°

0°

0.400 (0.016) TYP 3 PLACES

2.50 (0.098)

2.10 (0.083)

1.40 (0.055)

1.20 (0.047)

0.950 (0.0374) TYP

3.05 (0.120)

2.67 (0.105)

0.800 (0.031) TYP

1.12 (0.044)

0.81 (0.032)

0.10 (0.004)

0.013 (0.0005)

DIMENSIONS:

MM (INCH)

0.41 (0.016)

0.13 (0.005)

4-Pin SOT-143 (U)

MICREL INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com

This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use.

Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can

reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into

the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s

use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify

Micrel for any damages resulting from such use or sale.